Many pathologies cause or result in liver tissue lesions, known by the name of hepatic fibrosis. Hepatic fibrosis results in particular from an excessive accumulation of molecular compounds from the altered extracellular matrix in the hepatic parenchyma.
The stage of liver tissue damage, more particularly the nature and extent of the hepatic tissue lesions, is evaluated using a hepatic fibrosis score, in particular using the Metavir F score, which comprises 5 stages, from F0 to F4 (see Table 1 below). Determining the hepatic fibrosis score is of vital importance to the clinician, since it is a prognostic score.
In fact, the clinician uses this determination to decide whether or not to administer treatment in order to treat those lesions, or at least to reduce their effects. The clinician also bases a decision to start a treatment on this determination. In particular, when the hepatic fibrosis score is at most F1, the clinician will generally decide not to administer treatment, while when the score is at least F2, the administration of treatment is recommended irrespective of the degree of necrotico-inflammatory activity.
However, anti-HCV treatments cause major side effects for the patient. As an example, the accepted current treatment for patients infected with hepatitis C virus (HCV) comprises the administration of standard or pegylated interferon over a period which may be up to 48 weeks or longer. Regarding interferon, the side effects are frequent and numerous. The most frequent side effect is that of influenza-like syndrome (fever, arthralgia, headaches, chills). Other possible side effects are: asthenia, weight loss, moderate hair loss, sleep problems, mood problems and irritability, which may have repercussions on daily life, difficulties with concentrating and skin dryness. Certain rare side effects, such as psychiatric problems, may be serious and have to be anticipated. Depression may occur in approximately 10% of cases. This has to be identified and treated, as it can have grave consequences (attempted suicide). Dysthyroidism may occur. Furthermore, treatment with interferon is counter-indicated during pregnancy.
Regarding ribavirin, the principal side effect is haemolytic anaemia. Anaemia may lead to treatment being stopped in approximately 5% of cases. Decompensation due to an underlying cardiopathy or coronaropathy linked to anaemia may arise.
Neutropenia is observed in approximately 20% of patients receiving a combination of pegylated interferon and ribavirin, and represents the major grounds for reducing the pegylated interferon dose.
The cost of these treatments is also very high.
In this context, being able to determine, in a reliable manner, the hepatic fibrosis score of a given patient, and more particularly being able to discriminate, in a reliable manner for a given patient, a hepatic fibrosis score of at most F1 from a hepatic fibrosis score of at least F2 is of crucial importance to the patient.
Currently available means for determining the hepatic fibrosis score of a patient in particular comprises anatomo-pathologic examination of a hepatic biopsy puncture (HBP). This examination can be used to make a sufficiently reliable determination of the level of fibrosis, but there are considerable risks linked to the invasive mode of sampling. In order to be sufficiently reliable for a given patient, at the very least this examination has to be carried out on a sample of sufficient quantity (removal of a length of 15 mm using a HBP needle), and has to be examined by a qualified anatomo-pathologist. HBP is an invasive, expensive procedure, and is associated with a morbidity of 0.57%. It cannot be used to monitor patients in a regular manner in order to evaluate the progress of the fibrosis.
In the prior art, there are means which have the advantage of being non-invasive, such as:                Fibroscan™, which is a system for imaging the liver by transient elastography, and such as        Fibrotest™, Fibrometer™ and Hepascore™, which are multivariate classification algorithms combining the measurement values for seric proteins and optionally, values for certain clinical factors,        see WO 02/16949 A1 (in the name of Epigene), WO 2006/103570 A2 (in the name of Assistance Publique—Hôpitaux de Paris), WO 2006/082522 A1 (in the name of Assistance Publique—Hôpitaux de Paris), as well as their national and regional counterparts.        
Fibrotest™ (supplied by BioPredictive; Paris, France) uses measurements of alpha-2-macroglobulin (A2M), haptoglobin, apolipoprotein A1, total bilirubinaemia and gamma-glutamyl transpeptidase.
The Fibrometer™ (supplied by BioLiveScale; Angers, France) uses assays of platelets, the prothrombin index, aspartate amino-transferase, alpha-2-macroglobulin (A2M), hyaluronic acid, and urea.
Hepascore™ uses measurements of alpha-2-macroglobulin (A2M), hyaluronic acid, total bilirubin, gamma-glutamyl transpeptidase, and the clinical factors age and sex.
Fibroscan™ does not have sufficient sensitivity to differentiate a F1 score from a F2 score (see for example, Castera et al. 2005, more particularly FIG. 1A of that article).
Furthermore, while it now seems to be accepted that tests such as Fibrotest™, Fibrometer™ or Hepascore™, can be used to reliably identify a hepatic cirrhosis, in particular linked to HCV, these tests do not have the capacity of precisely and reliably identifying the earlier stages of fibrosis and do not have the capacity to differentiate the F1 stage from the F2 stage of fibrosis for a given patient in a reliable manner (see for example, Shaheen et al. 2007).
Thus, there is still a need for means that can be used to determine, in a precise and reliable manner, the stage of hepatic tissue damage, more particularly the hepatic fibrosis score of a given patient. More particularly, there is still a clinical need for means that can be used to reliably distinguish, for a given patient, whether a fibrosis is absent, minimal or clinically not significant (Metavir score F0 or F1), a moderate or clinically significant fibrosis (Metavir score F2 or higher), more particularly to distinguish, in a reliable manner for a given patient, a F1 fibrosis (fibrosis without septa) from a fibrosis F2 (fibrosis with some septa). In particular, there is still a clinical need for means that can be used to detect the appearance of the first septa in a reliable manner.
The invention of the application proposes means that can in particular satisfy these needs.